M. Bikrani et al., Rhodium(I) carbonyl complexes with alpha-diimine ligands containing amino or hydroxy substituents, TRANSIT MET, 24(4), 1999, pp. 394-397
alpha-Diimines, RN:C(R')C(R'):NR''(LL) derived from glyoxal, GLL (R' = H) a
bbreviated as GAA (R = R'' = 4-dimethylaminophenyl) or GHA (R = R'' = 4-hyd
roxyphenyl), and derived from biacetyl, BLL (R' = Me) abbreviated as BDH (R
= R'' = NH2), BOH (R = NH2, R'' = OH) react with carbonylrhodium(I) compou
nds to give different products depending on the imino substituents in the l
igand and/or the solvent employed. The reaction of alpha-diimines bearing a
mino groups, such as GAA or BDH with [RhCl(CO)(2)](2) in acetone yields bin
uclear [RhCl(CO)(2)](2)(mu-LL) while in CH2Cl2 ionic [Rh- (CO)(2)(LL)](+)[R
hCl2(CO)(2)](-) species are obtained. In acetone [RhCl(CO)(2)](2)(mu-GAA) e
xists as an equilibrium mixture between two different neutral binuclear spe
cies; [Rh(CO)(2)(BDH)](+) exists as a mixture of two species containing che
late or monodentate bonded diimine respectively. GAA or BDH react "in situ"
with [RhCl(CO)(C2H4)](2) in benzene to yield tetracoordinated monocarbonyl
ated [RhCl(CO)(LL)] compounds. alpha-Diimines (LL) bearing hydroxy groups,
such as GHA or BOH react with [RhCl(CO)(2)](2) or "[RhCl(CO)(C2H4)](2)" to
give pentacoordinated dicarbonylated [RhCl(CO)(2)(LL)] compounds.